1. Field of the Invention
The present invention relates to an ink-jet recording apparatus and in particular relates to an ink-jet recording apparatus in which ink is supplied from a main tank installed outside of a carriage to a recording head mounted on the carriage. Furthermore, the present invention relates to an ink-jet recording apparatus in which ink is supplied to a recording head by inserting an ink supplying needle into a sealing member for sealing an open mouth of an ink storing device such as an ink bag or an ink tank, and to the ink storing device.
2. Discussion of the Related Art
In an ink-jet recording apparatus, there has been conventionally devised a method for supplying ink from an ink tank of a large capacity installed outside of a carriage to a recording head mounted on the carriage in order to reduce a running cost and increase a printing speed. In this case, a method for reserving the ink in a flexible ink bag has been known as a method for storing a large quantity of ink in the ink tank.
As one example of such a prior art, Japanese Patent Laid-Open No. 56-44663 (1981) discloses the configuration in which a flat and thin container made of a high molecular film is disposed under a printer unit.
Alternatively, Japanese Patent Laid-Open No. 57-18265 (1982) discloses the configuration in which a flexible ink bag of a flat and thin type is used as a main tank so as to absorb pressure variations generated by air staying inside a sub tank.
Otherwise, Japanese Patent Laid-Open No.57-63286 (1982) discloses the configuration in which an ink tank is made of a flexible film having a low gas permeability so as to reduce the inner volume of the ink tank by the atmospheric pressure as ink is consumed.
Additionally, Japanese Patent Laid-Open No. 63-35346 (1988) discloses an ink bag formed of two flexible films bonded to each other and welded at four sides thereof by thermal fusion. An open mouth for letting out ink from the inside of the ink bag is welded onto one side of the ink bag by thermal fusion. A communicating hole communicating with the outside is formed at the open mouth. A rubber plug is press-fitted into the communicating hole, to thus seal the open mouth. Consequently, the ink can be introduced outside of the ink bag via an ink supplying needle by piercing the ink supplying needle through the rubber plug.
Moreover, Japanese Patent Laid-Open No. 4-34765 -1992) discloses an ink bag in which an open mouth is welded onto one side of the ink bag made of a flexible film by thermal fusion in the same manner as in Japanese Patent Laid-Open No. 63-35346, and a rubber plug is fitted into a communicating hole formed at the opening in a sealed state by press-fitting, caulking, bonding or the like. Here, a thin film is formed at a portion of the open mouth in contact with the rubber plug. Therefore, the ink supplying needle penetrates the rubber plug and the thin film of the open mouth to define an ink supplying path, thereby letting out the ink contained in the ink bag to a recording head.
However, in the case where the ink bag having flexibility is used as the ink tank as described above, there have arisen the following inconveniences:
The flexible ink bag of a flat and thin type is filled with ink, and then, is contained inside an ink tank casing, for supplying the ink. Therefore, the volume of the ink bag of a flat and thin type is smaller than that of the casing, thereby enlarging an unusable dead space. This results in the inconvenience that the ink tank cannot have a compact configuration. Otherwise, in order that a large quantity of ink is reserved in the ink bag of a flat and thin type, the area of a flat side face (hereinafter referred to as "a flat surface") must be extended, so that the ink tank having a markedly large flat surface must be used. It is very inconvenient that such an ink tank is housed inside an ink-jet recording apparatus.
In order to overcome the above-described inconveniences, there has been disclosed an ink bag which is neither flat nor thin but is formed into a polygonal prism or has a foldable side face. For example, Japanese Utility Model Laid-Open No. 60-64846 (1985) discloses an ink bag having a foldable side face in which an end edge of a foldable member is thermally fused inside of both end edges of a pair of main body films. Alternatively, Japanese Patent Laid-Open No. 5-254144 (1993) discloses a flexible ink bag which is in the form of a polygonal prism in a state that it is filled with a sufficient quantity of ink.
However, there has arisen inconvenience that a decrease in ink quantity remaining in the ink bag causes irregular wrinkles or creases which prevent the ink bag from being completely deflated, and therefore, the ink remains in the ink bag.
Furthermore, in an ink-jet recording apparatus dislcosed in Japanese Patent Laid-Open No. 63-35346 and No. 4-347653, the ink supplying needle penetrates the rubber plug to define the ink supplying path for letting out the ink, therefore, the ink supplying needle may be possibly inserted into the used ink bag to fill the ink bag with the ink for reuse. In the case where the ink to be refilled is inappropriate, there occurs a possibility of a printing fault due to deficient ejection.
Furthermore, in an ink-jet recording apparatus disclosed in Japanese Patent Laid-Open No. 4-347653, the ink supplying needle penetrates the thin film of the open mouth, thereby inducing a possibility that broken pieces of the broken thin film may be contained in the ink.